1. Field of the Invention
The present invention relates to a frontbody structure for an automobile and more particularly to a frame structure of a frontal portion of an automobile body.
2. Description of the Prior Art
In a frame structure of the front portion of a conventional automobile, respective rear ends of left and right front frames extending longitudinally along respective left and right side walls of an engine room are connected at an inclined portion of a toe board partitioning between the engine room and a passenger compartment with front ends of left and right side frames connected to the underneath of a floor, in the event of a collision, so as to diffusively transfer an impact load inputted from the front frame to the floor and the like through the toe board and the side frame.
A drawback of this frame structure is a difficulty in transferring the impact load to the side frame in a stable manner in the event of a collision and as a result it has such a problem that a lower curved portion of the toe board is deformed being projected in the direction of the passenger compartment due to a concentrated impact load.
Hitherto, numerous approaches have been made to increase the rigidity of the connecting portion of the front frame with the toe board. For example, Japanese Utility Model Application Laid-open No. Jitsu-Kai-Shou 63-43881 discloses an approach in which a reinforcement member is secured from the passenger compartment side to the lower curved portion of the toe board at the connecting portion of the front frame with the toe board so as to be connected at one end thereof with an upper central portion of the toe board and at the other end thereof with the side frame. This approach contemplates that the reinforced curved portion of the toe board enables a diffusion of the impact load transmitted from the front frame to the toe board toward the side frame and the floor tunnel.
However, this prior art such as exemplified by the aforesaid approach is still inadequate in the diffusion of the impact load at the event of an offset collision or an oblique collision. Yet, an additional use of the reinforcement member leads to a further increase of the vehicle weight and this is retrogressive in terms of the weight reduction.